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随着城市的快速发展,城市地下空间日趋紧张,利用市政公用隧道敷设高压电缆在世界范围内已经被广泛采用。近年来,随着以地铁为代表的城市交通大规模规划建设,利用地铁富余空间敷设电缆高压具有广阔的发展前景。在以直流供电系统供电的轨道交通中,作为回流通路的轨道往往不能做到对地完全绝缘,这就导致了一部分电流泄漏形成杂散电流,敷设于轨道附近的电缆外表导电层中同样会产生杂散电流。杂散电流会对随地铁敷设的高压电缆产生腐蚀,从而给电缆的长期安全稳定运行带来严重的危害。以南京地铁为例,依据地铁隧道工程图建立了地铁隧道内电阻分布的网络拓扑结构,并通过Matlab建模仿真对比了机车在单边供电和双边供电、加排流网和不加排流网以及排流网两端与轨道相连和排流网两端与电缆相连等不同工况下的杂散电流的分布情况,同时指出了杂散电流带来的危害以及必要的防护措施。
With the rapid development of the city, the urban underground space is becoming increasingly tense. The laying of high-voltage cables using municipal public tunnels has been widely adopted in the world. In recent years, with the large-scale planning and construction of urban transport represented by the subway, it is expected that the laying of the cable high voltage using the spare space of the subway will have broad prospects for development. In the case of rail transit powered by a DC power supply system, the track as the return path can not be completely insulated from the earth. This results in a part of the current leakage resulting in a stray current which is also applied to the outer conductor of the cable in the vicinity of the track Stray current is generated. Stray current will corrode the high-voltage cables laid along with the subway, which will bring serious harm to the long-term safe and stable operation of the cables. Taking Nanjing metro as an example, the network topology of the resistance distribution in metro tunnel is established according to the subway tunnel engineering drawings. By using Matlab modeling and simulation, the comparison between locomotive on single-side power supply and bilateral power supply, with and without drainage net As well as the distribution of stray current under different conditions such as the connection between the two ends of the drainage net and the track and the connection of the two ends of the drainage net to the cable. At the same time, the hazards caused by the stray current and the necessary protective measures are pointed out.